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<head>
  <meta charset="UTF-8">
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  <title>Document</title>
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<body>
  <script>
    // 只是数组长度增加，地址值没变
    const arr = [1, 2]
    arr.push(3)
    console.log(arr)

    //地址值改变
    const arr1 = []
    arr1 = [1, 2, 3]
    console.log(arr1)
  </script>
</body>

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